title: Knockdown of core binding factorβ alters sphingolipid metabolism.
abstract: Core binding factor (CBF) is a heterodimeric transcription factor containing one of three DNA-binding proteins of the Runt-related transcription factor family (RUNX1-3) and the non-DNA-binding protein, CBFβ. RUNX1 and CBFβ are the most common targets of chromosomal rearrangements in leukemia. CBF has been implicated in other cancer types; for example RUNX1 and RUNX2 are implicated in cancers of epithelial origin, including prostate, breast, and ovarian cancers. In these tumors, CBF is involved in maintaining the malignant phenotype and, when highly over-expressed, contributes to metastatic growth in bone. Herein, lentiviral delivery of CBFβ-specific shRNAs was used to achieve a 95% reduction of CBFβ in an ovarian cancer cell line. This drastic reduction in CBFβ expression resulted in growth inhibition that was not associated with a cell cycle block or an increase in apoptosis. However, CBFβ silencing resulted in increased autophagy and production of reactive oxygen species (ROS). Since sphingolipid and ceramide metabolism regulates non-apoptotic cell death, autophagy, and ROS production, fumonsin B1 (FB1), an inhibitor of ceramide synthase, was used to alter ceramide production in the CBFβ-silenced cells. FB1 treatment inhibited the CBFβ-dependent increase in autophagy and provided a modest increase in cell survival. To document alterations to sphingolipids in the CBFβ-silenced cells, ceramide, and lactosylceramide levels were directly examined by mass spectrometry. Substantial increases in ceramide species and decreases in lactosylceramides were identified. Altogether, this report provides evidence that CBF transcriptional pathways control cellular survival, at least in part, through sphingolipid metabolism.
authors.affiliation: Department of Biochemistry and Molecular Biology and Feist-Weiller Cancer Center, LSUHSC School of Medicine in Shreveport, Shreveport, Louisiana.
authors.forename: Adam H
authors.initials: AH
authors.lastname: Greer
authors.forename: Thomas
authors.initials: T
authors.lastname: Yong
authors.forename: Katie
authors.initials: K
authors.lastname: Fennell
authors.forename: Yara W
authors.initials: YW
authors.lastname: Moustafa
authors.forename: Marcie
authors.initials: M
authors.lastname: Fowler
authors.forename: Floyd
authors.initials: F
authors.lastname: Galiano
authors.forename: Shu-Wing
authors.initials: SW
authors.lastname: Ng
authors.forename: Ross S
authors.initials: RS
authors.lastname: Berkowitz
authors.forename: James
authors.initials: J
authors.lastname: Cardelli
authors.forename: Shari
authors.initials: S
authors.lastname: Meyers
authors.forename: J Nathan
authors.initials: JN
authors.lastname: Davis
mesh_terms: D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism; D017209:Apoptosis / Q000235:genetics; D001343:Autophagy / Q000235:genetics; D002453:Cell Cycle / Q000235:genetics; D002460:Cell Line; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000235:genetics; D050676:Core Binding Factor Alpha 2 Subunit / Q000235:genetics / Q000378:metabolism; D050658:Core Binding Factor beta Subunit / Q000172:deficiency* / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D005260:Female; D055785:Gene Knockdown Techniques; D057809:HEK293 Cells; D006801:Humans; D007790:Lactosylceramides / Q000235:genetics / Q000378:metabolism; D010051:Ovarian Neoplasms / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D013107:Sphingolipids / Q000235:genetics / Q000378:metabolism*
chemical_list: D015703:Antigens, CD; D050676:Core Binding Factor Alpha 2 Subunit; D050658:Core Binding Factor beta Subunit; D004268:DNA-Binding Proteins; D007790:Lactosylceramides; C493728:RUNX1 protein, human; D017382:Reactive Oxygen Species; D013107:Sphingolipids; C009744:CDw17 antigen